1 files changed, 79 insertions, 0 deletions
diff --git a/runtime/arith.c b/runtime/arith.c
new file mode 100644
index 00000000..175cc4e8
--- /dev/null
+++ b/runtime/arith.c
@@ -0,0 +1,79 @@
+#ifndef _ARITH_C_ /* -*- linux-c -*- */
+#define _ARITH_C_
+
+/** @file arith.
+ * @brief Implements 64-bit signed division/multiplication.
+ */
+
+struct context;
+void _stp_divmod64 (unsigned *errorcount, int64_t x, int64_t y,
+                    int64_t *quo, int64_t *rem);
+
+
+/** Divide x by y.  In case of overflow or division-by-zero,
+ * increment context errorcount, and return any old value.
+ */
+inline int64_t _stp_div64 (unsigned *errorcount, int64_t x, int64_t y)
+{
+  if (likely ((x >= LONG_MIN && x <= LONG_MAX) &&
+              (y >= LONG_MIN && y <= LONG_MAX)))
+    {
+      long xx = (long) x;
+      long yy = (long) y;
+      // check for division-by-zero and overflow
+      if (unlikely (yy == 0 || (xx == LONG_MIN && yy == -1)))
+        {
+          (*errorcount) ++;
+          return 0;
+        }
+      return xx / yy;
+    }
+  else
+    {
+      int64_t quo = 0;
+      _stp_divmod64 (errorcount, x, y, &quo, NULL);
+      return quo;
+    }
+}
+
+
+/** Modulo x by y.  In case of overflow or division-by-zero,
+ * increment context errorcount, and return any old value.
+ */
+inline int64_t _stp_mod64 (unsigned *errorcount, int64_t x, int64_t y)
+{
+  if (likely ((x >= LONG_MIN && x <= LONG_MAX) &&
+              (y >= LONG_MIN && y <= LONG_MAX)))
+    {
+      long xx = (long) x;
+      long yy = (long) y;
+      // check for division-by-zero and overflow
+      if (unlikely (yy == 0 || (xx == LONG_MIN && yy == -1)))
+        {
+          (*errorcount) ++;
+          return 0;
+        }
+      return xx % yy;
+    }
+  else
+    {
+      int64_t rem = 0;
+      _stp_divmod64 (errorcount, x, y, NULL, &rem);
+      return rem;
+    }
+}
+
+
+/** Perform general long division/modulus. */
+void _stp_divmod64 (unsigned *errorcount, int64_t x, int64_t y,
+                    int64_t *quo, int64_t *rem)
+{
+  // XXX: wimp out for now
+  (*errorcount) ++;
+  if (quo) *quo = 0;
+  if (rem) *rem = 0;
+}
+
+
+
+#endif /* _ARITH_C_ */